Three families of multiarmed and multicationic gemini surfactants, having pentaerythritol, dipentaerythritol, or adamantane cores, were synthesized and examined for their colloidal properties in water. Geminis with four or six six-carbon chains are highly water-soluble and do not self-assemble. But surface tension and conductivity measurements show that the geminis with four or six eight-carbon chains form micelles in the 3-6 mM range (compared to 0.5 M for a corresponding surfactant with a single chain). According to dynamic light scattering, these micelles are small (<30 Å diameter); no evidence of dendritic growth below 25 mM is evident. Geminis with four or six 12-carbon chains are too water-insoluble to examine for micelle formation. It is concluded the outward projection of the hydrocarbon chains in water greatly enhances the propensity of the surfactants to self-assemble. Micellar growth is seemingly restricted by chain pairing, chain looping, and associative ring formation. Since the aggregates have, despite these effects, greater residual water-hydrocarbon contact than found in typical micelles, water solubility of surfactants having longer chains is impaired.

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Purpose The aim of this study was to create and assess biological activity of a new compound based on carnosine and acetylsalicylic acid (ASA) that will comprise antioxidant effect with antiplatelet activity, while simultaneously preventing side effects on the gastrointestinal tract. Methods Salicyl-carnosine (SC) was synthesized by condensation of ASA and carnosine. Antioxidant activity was determined by spectrophotometric and chemiluminescence methods. Antiplatelet activity was carried out by the light transmissionaggregometry method using the inductor ADP. Chronic gastric ulcer in rats was modeled using glacial acetic acid. Results Using SOD-like activity, iron-induced chemiluminescence, BaSO4-activated respiratory burst, and evaluation of red blood cell structure stabilization during oxidative damage induced by sodium hypochlorite, it was shown that SC possesses antioxidant activity analogous, or better, than that of carnosine. Antiplatelet activity of SC was evaluated in the blood of healthy individuals, and was also shown to be comparable to, or exceeding that of ASA. Also SC demonstrates high resistance to hydrolysis by tissue and serum carnosinases. Most importantly, it was shown that SC has protected the gastric mucosa against the formation of stomach ulcerative lesions and promoted their epithelization, therefore overcoming the undesirable inherent side effects of ASA. Conclusions SC preserves pharmacologically significant properties of ASA and carnosine while retaining an anti-ulcer activity and resistance to the carnosinase hydrolysis at the same time. These properties are particularly promising for the potential development of new anti-inflammatory and antithrombotic drugs. KeywordsCarnosine . Acetylsalicylic acid . Salicylic acid . Antioxidant . Antiplatelet action . Gastrointestinal ulcer Abbreviations ASA acetylsalicylic acid CL chemiluminescence COX cyclooxygenase HPLC high performance liquid chromatography HRMS high resolution mass spectrometry LP lipoproteins LPO lipid peroxidation NBT nitroblue tetrazolium NSAIDs non-steroidal anti-inflammatory drugs

Spherical polycationic brushes (SPBs) were synthesized by grafting polycationic chains onto 100 nm polystyrene particles. These particles were exposed to unilamellar egg-lecithin (EL) liposomes with a mean diameter of 40 nm that had been rendered anionic via the presence of 10 molar% of phosphatidylserine (PS(1-)). The liposomes also contained 30 mole% of a morpholinocyclohexanol-based lipid (MOCH) that undergoes a conformational flip when the pH is decreased from 7.0 to 5.0. Mixtures of SPBs and liposomes at pH 7 gave an electrostatically-driven complex possessing, on average, about 40 liposomes for each SPB particle. It was found that the bound liposomes rapidly release much of their contents when the pH is reduced from 7.0 to 5.0 owing mostly to a MOCH conformational change that creates defects in the bilayer membrane. The drop in pH does not, however, induce a separation of the liposomes from the SPBs. Around 50-60% of the liposome contents escape before, it is reasoned, lateral and transmembrane motion of the membrane components heals the defects and prevents further release. Remarkably, the liposomes complexed with SPB release their cargo much faster than the identical but non-complexed liposomes.

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